The conventional method of washing textiles in an automatic home-type washing machine in the United States is carried out in either a top loading or front loading machine. The difference between the two machines is that in a top loader the wash basket is rotatable around a substantially vertical axis and in a front loader the wash basket is rotatable around a substantially horizontal axis. Home-type loading machines are, by far, the most popular, comprising about 90% of the United States' automatic washing machine market.
The process for washing textiles in a home-type top loader begins by placing the textiles in the wash basket. In a normal capacity home-type top loader the wash basket can hold up to about 7 kilograms of textiles. Detergent composition is then added to the wash basket. Finally, water, which is typically heated, is added to the wash basket to form a water and detergent solution known as the wash liquor. Thus, formation of the wash liquor is carried out in the wash basket in the presence of the textiles to be washed. The washing step is then completed by applying mechanical agitation to the system in order to loosen and remove the soil from the textiles.
The temperature and level of water and level of detergent composition used in the wash step can vary. About 60% of the wash steps use warm water (typically around 35.degree. C.), with the balance being evenly split between hot water (typically around 50.degree. C.) and cold water (typically around 15.degree. C.). The level of water and detergent composition used in this step typically ranges from about 40 liters to about 90 liters and from about 20 grams to about 145 grams, respectively, depending upon the wash basket size and load size. The resulting detergent composition concentration in the wash liquor is from about 210 parts per million (ppm) to about 3,600 ppm.
The wash liquor is then removed and the textiles are rinsed. The rinse step normally comprises adding clear water to the wash basket. Mechanical agitation is normally applied during the rinse step to remove the detergent composition from the textiles. Finally, the water is drained and the textiles are spun to mechanically remove as much water as possible. A cold water rinse is used in about 60% of the rinse steps, with the balance being warm water rinses. The amount of water used in this step is typically the same as that used in the wash step. The rinse step is generally repeated one or more times.
The wash cycle of the home-type front loader is very similar to that of the home-type top loader. The temperature of water and detergent composition concentration used in the washing step are very similar to a home-type top loader. The basic difference is that the amount of water used in each of the wash and rinse steps typically ranges from about 25 liters to about 35 liters and, thus, the level of detergent composition is from about 10 grams to about 70 grams.
The complete conventional automatic wash process in a home-type top loader typically uses from about 130 liters to about 265 liters of water. By way of contrast, a home-type front loader, though more efficient, typically uses about 95 liters of water. This too is a considerable water expenditure for one wash cycle. Also, if the water is heated, there is a considerable energy expenditure. Both water and energy are costly to the consumer.
A known drawback normally exhibited by conventional automatic wash processes of the foregoing type is that soil redeposition occurs in both the wash and rinse steps. Soil redeposition is soil that is detached from the textiles and goes into the wash or rinse liquor and is then redeposited onto the textiles. Thus, soil redeposition substantially limits the "net" cleaning performance.
Another known drawback normally exhibited by conventional automatic wash processes of the foregoing type is that dye transfer can occur when dealing with loads of differently colored textiles. Dye transfer is the detachment of dye from a textile into the wash liquor and its subsequent deposition onto another textile. To avoid dye transfer the consumer has found it necessary to perform the additional step of presorting the textiles, not only by textile type but also by color type.
U.S. Pat. No. 4,344,198 issued to Arendt et al on Aug. 17, 1982 claims a process for the washing of clothes through a wash and rinse cycle in a washing machine with a horizontal, perforated, driven tub arranged inside a housing wherein the tub has at its rotating periphery a tangential area, in which during the washing and rinsing cycle as the tub rotates, the clothes are repeatedly lifted up and then fall in a trajectory path onto the lower portion of the tub and are then distributed without unbalance to the tub, as the tub velocity is gradually increased. The clothes are then centrifuged as the velocity is increased further. According to Arendt, his improvement comprises the steps of wetting the clothes with an amount of suds that gives a "doughy" consistency to the clothes by filling the tub with suds until the level of suds does not significantly rise above the tangential area of the tub by maintaining in the tub during washing an aqueous medium level of at least about 5% of the tub's diameter, whereby the dry clothes are loaded individually into the tub which rotates at a speed at which the centrifugal velocity at the tub case is about 0.3-0.8 g. The tub speed is then increased to about 1 g. then gradually changed to a spin speed and after the spinning, reduced to a velocity in keeping with the loading speed. The process is thereafter followed with a rinse cycle which is similar to the washing cycle. According to Arendt, the exchange between "engaged" and "free" medium is achieved not so much by leaching but by the mechanical action of the tub. Finally, Arendt teaches that water is saved for the most part not by using smaller ratios of total media, but by reducing the number of wash and rinse cycles.
U.S. Pat. No. 4,118,189 issued to Reinwald et al on Oct. 3, 1978 discloses a wash process which consists of transforming a concentrated wash liquor, by the introduction of compressed air, into a foam which is thereafter applied to the soiled textiles. The textiles are mechanically agitated in the foam for at least thirty seconds, then the foam is destroyed and removed from the textiles by spinning the textiles in a rotary perforated drum. This cycle is repeated at least five times, followed by conventional rinsing. Reinwald suggests that the dirt detached from the textile material and dispersed in a relatively highly concentrated detergent solution is partially deposited again on the textile fiber during the subsequent rinsing due to a dilution of the wash liquor.
Still another attempt at using more concentrated wash liquor without encountering redeposition problems of the type discussed in the aforementioned patent issued to Reinwald is disclosed in U.S. Pat. No. 3,650,673 issued to Ehner on Mar. 21, 1972. Ehner discloses method and apparatus for washing textiles utilizing an amount of water corresponding to about 50% to 150% of the dry weight of the textiles. The process consists of placing such quantities of water, the textiles to be laundered and a transfer agent, e.g., polyethylene foam having a large surface area per unit mass, in a rotatable enclosure similar to those employed in a front loader type washing machine and tumbling these materials together for a period of time. Soils removed from the textiles by the tumbling action are distributed over the combined exposed surface areas of the textiles and the transfer agent, which is subsequently separated from the textiles. Thus, the textiles are cleansed of the soils distributed onto the transfer agent. Ehner admits that a quantity of soil will be left on the textiles, but teaches that it will be substantially reduced from the original quantity and will be distributed so as to leave no objectionable areas of soil concentration. Following separation of the soil carrying transfer agent from the textiles, the textiles are subsequently dried in the same rotatable enclosure in which they are "washed" by tumbling them while circulating warm dry air therethrough.
U.S. Pat. No. 3,647,354 issued to Loeb on Mar. 7, 1972 suggests that a wash process such as that disclosed in the aforementioned Ehner patent be followed by a rinse process employing a quantity of water sufficient only to bring the textiles to a condition of dampness. According to Loeb, the textiles are tumbled in a rotating drum with a clean transfer agent which functions in a manner similar to the transfer agent used in the wash process to separate detergent and loosened soils from the textiles.
Despite the advantages allegedly provided by wash processes of the foregoing type, they have not met with widespread commercial acceptance, particularly in the home laundry market.
Accordingly, an object of the present invention is to provide apparatus and process for laundering textiles using a small amount of water, yet minimizing soil redeposition and dye transfer, even without presorting of the textiles to be laundered.
Another object of the present invention is to provide apparatus and process for laundering textiles which makes extremely efficient use of the detergent composition utilized and, if applied, extremely efficient use of heat energy.
Another object of the present invention is to provide preferred apparatus and process for laundering textiles using cold water.
A further object of the present invention is to provide apparatus and process for laundering textiles which results in superior cleaning as well as preservation of the textiles' appearance over many laundering cycles.
A still further object in a preferred aspect of the present invention is to provide apparatus and process for laundering textiles wherein mechanical energy can be applied to textiles which have been contacted with a concentrated wash liquor without creating a suds problem.
A still further object of the present invention is to provide wash liquor compositions and detergent compositions for use in said apparatus and process.